The invention relates to an event construction, comprising a public area, such as a grandstand, and a pitch for performing activities, for example sporting activities like football and baseball, which pitch is accommodated on a floor which by means of sliding means is set up in such a way that it can be moved in relation to the public area, which sliding means comprise at least one elongated track which is set up underneath the floor and is connected to the base or to the floor, and also supporting means which are connected to the floor and can be slid in relation to the track, or supporting means connected to the base, over which supporting means the elongated track can be slid.
Such a construction is known from NL-A-9300182. A number of steel elements are accommodated in the base, which elements serve as slide tracks. These elements support a number of feet of a casing containing a grass mat. Each foot has at its bottom end a PTFE-containing plastic sheet, which is slidable with low friction over the steel element.
On the one hand, the steel elements must be sturdily supported in the base, which can consist of, for example, a concrete foundation slab. On the other hand, small relative movements must be possible, in view of possible settlement and differences in expansion. The costs of such a construction are consequently relatively high.
The object of the invention is to provide a construction of the abovementioned type which does not have these disadvantages. That object is achieved by the fact that each track consists of mortar material.
The tracks made of mortar material can be manufactured in a simple manner with great accuracy as regards the levelness of the sliding surface, and consequently provide an even support for the floor situated above, in which a pitch is accommodated. It is possible to treat the surface area of the sliding surface after the mortar material has set, in such a way that the coefficient of friction is as low as possible. Such a treatment can be, for example, a polishing treatment.
An example which can be mentioned is a cast mortar based on plastic, such as an epoxy resin, which is preferably a two-component epoxy resin.
The mortar can also contain stony granules, such as sand or fine gravel, with a granule size between 0.25 and 4 mm. After the mortar material has set, it must have the maximum compression strength, which lies between 30 and 150 N/mm2.
A reinforcement is preferably incorporated in the mortar material, in order to increase the maximum permissible tensile load of the mortar material. This gives the tracks good ability to withstand the tensile forces created in the tracks during shifting of the pitch
The tracks of mortar material can be sunk in the base, such as a concrete slab. For that purpose, such a slab has a trench made in it, after which the reinforcement is placed in said trench and the mortar material applied.
Furthermore, each track of mortar material can be covered with a friction-reducing paint layer.
In order to rule out the possibility of such a paint layer peeling off as a result of rising damp, the mortar when it has set must be impermeable to vapour.
The paint layer can comprise a first coat and at least one top coat. This first coat and top coat can each consist of a two-component epoxy resin; the top coat can also contain wear-resistant pigments. After it has dried, the paint layer must preferably be able to withstand a maximum surface pressure which lies between 5 and 80 N/mm2. In addition, in the pull-off test the value obtained for this layer must preferably lie between 0.5 and 20 N/mm2.
The thickness of the first coat preferably lies between 30 and 50 xcexcm; that of a top coat between 120 and 350 xcexcm.
Two or more top coats can also be provided, the total thickness of the paint layers lying between 150 and 7000 xcexcm. It is also possible to reverse the elongated track and the supporting means; the supporting means can be placed in or on the foundation slab, and the elongated track can be fixed to and/or manufactured on the underside of the movable floor.
Another variant can consist of the supporting means comprising elongated tracks, the sliding surface part of which is also made of mortar material, which can further be provided with a friction-reducing paint layer. In this variant both sliding surfaces can be made of mortar material.